Chrysidid generalities

Chrysidids (Hymenoptera Chrysididae) are Apocrita wasps characterized by a colorful habit with metallic glares (thus the common local names Gold wasps, Goldwespen, Guêpes dorées, Vespe dorate). Although belonging to the group of the Aculeate wasps, considered obsolete nowadays, Chrysidids present a reduction of the stinging apparatus to an internal telescopic apparatus: the ovipositor in females and the genital tube in males.

Biology: chrysidids are parasitoids and cleptoparasites of other insects (other wasps, above all), from which the name of Cuckoo wasps.

As far as the morphology is concerned, Chrysidids differ from the other Aculeate wasps for the reduction of the number of the external abdominal segments, for the presence of 11 antennal articles and for the wing veins with 5 closed cells. Some tropical species have apterous females and a body without metallic reflections.

The shining coloration made of iridescent blue, green, purple is an interference coloration, while true pigments (red, brown and white) are very rare. The typical brilliance is emphasized by the exoskeleton sculpture, which is carved by a complex punctuation and by projections, crests, holes from micrometric to millimetric size.

Distinction of sexes: in some subfamilies (Cleptinae, Amiseginae, Loboscoelidinae) the distinction is immediate, being based on the different number of the visible abdominal segments: 5 visible segments in males and 4 in females; in Parnopinae there are 4 visible segments in males and 3 in females. In Chrysidinae, it needs sometimes the extraction and the exam of the genital apparatus.

Currently about 3,000 species have been described in the entire world, distributed in 83 Genera and in 5 subfamilies, following Kimsey & Bohart (1991) and more recent studies. Among those, about 250 taxa are known in Italy. Chrysidids are distributed all over the world, but southern Asia, Africa and Middle East have not yet been explored systematically. As for each systematic group in nature, other hundreds of unknown species are expected to be described.